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Gen Comp Endocrinol. 2012 Jul 1;177(3):305-14. doi: 10.1016/j.ygcen.2012.02.013. Epub 2012 Feb 26.

Gonadotropin-inhibitory hormone (GnIH): discovery, progress and prospect.

Author information

1
Laboratory of Integrative Brain Sciences, Department of Biology, Waseda University, and Center for Medical Life Science of Waseda University, Tokyo 162-8480, Japan. k-tsutsui@waseda.jp

Abstract

A hypothalamic neuropeptide, gonadotropin-releasing hormone (GnRH), is the primary factor regulating gonadotropin secretion. An inhibitory hypothalamic neuropeptide for gonadotropin secretion was, until recently, unknown, although gonadal sex steroids and inhibin can modulate gonadotropin secretion. Findings from the last decade, however, indicate that GnRH is not the sole hypothalamic regulatory neuropeptide of vertebrate reproduction, with gonadotropin-inhibitory hormone (GnIH) playing a key role in the inhibition of reproduction. GnIH was originally identified in birds and subsequently in mammals and other vertebrates. GnIH acts on the pituitary and on GnRH neurons in the hypothalamus via a novel G protein-coupled receptor (GPR147). GnIH decreases gonadotropin synthesis and release, inhibiting gonadal development and maintenance. Such a down-regulation of the hypothalamo-pituitary-gonadal (HPG) axis may be conserved across vertebrates. Recent evidence further indicates that GnIH operates at the level of the gonads as an autocrine/paracrine regulator of steroidogenesis and gametogenesis. More recent evidence suggests that GnIH also acts both upstream of the GnRH system and at the level of the gonads to appropriately regulate reproductive activity across the seasons and during times of stress. The discovery of GnIH has fundamentally changed our understanding of hypothalamic control of reproduction. This review summarizes the discovery, progress and prospect of GnIH, a key regulator of vertebrate reproduction.

PMID:
22391238
PMCID:
PMC3378827
DOI:
10.1016/j.ygcen.2012.02.013
[Indexed for MEDLINE]
Free PMC Article

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